Cassini was born at the Paris Observatory. Admitted at the age of seventeen to membership of the French Academy of Sciences, he was elected in 1696 a fellow of the Royal Society of London, and became maitre des comptes in 1706. Having succeeded to his fathers position at the observatory in 1712, he measured in 1713 the arc of the meridian from Dunkirk to Perpignan, and published the results in a volume entitled De la grandeur ci de la figure de la terre (1720). He wrote besides Elimens d'astronomie (1740), and died at Thury, near Clermont.

He published the first tables of the satellites of Saturn in 1716.